TY  - JOUR
A1  - Hoff, Ulrike
A1  - Biskaborn, Boris
A1  - Dirksen, Veronika G.
A1  - Dirksen, Oleg
A1  - Kuhn, Gerhard
A1  - Meyer, Hanno
A1  - Nazarova, Larisa B.
A1  - Roth, Alexandra
A1  - Diekmann, Bernhard
T1  - Holocene environment of Central Kamchatka, Russia: Implications from a multi-proxy record of Two-Yurts Lake
JF  - Global and planetary change
N2  - Within the scope of Russian German palaeoenvironmental research, Two-Yurts Lake (TYL, Dvuh-Yurtochnoe in Russian) was chosen as the main scientific target area to decipher Holocene climate variability on Kamchatka. The 5 x 2 km large and 26 m deep lake is of proglacial origin and situated on the eastern flank of Sredinny Ridge at the northwestern end of the Central Kamchatka Valley, outside the direct influence of active volcanism. Here, we present results of a multi-proxy study on sediment cores, spanning about the last 7000 years. The general tenor of the TYL record is an increase in continentality and winter snow cover in conjunction with a decrease in temperature, humidity, and biological productivity after 5000-4500 cal yrs BP, inferred from pollen and diatom data and the isotopic composition of organic carbon. The TYL proxy data also show that the late Holocene was punctuated by two colder spells, roughly between 4500 and 3500 cal yrs BP and between 1000 and 200 cal yrs BP, as local expressions of the Neoglacial and Little Ice Age, respectively. These environmental changes can be regarded as direct and indirect responses to climate change, as also demonstrated by other records in the regional terrestrial and marine realm. Long-term climate deterioration was driven by decreasing insolation, while the short-term climate excursions are best explained by local climatic processes. The latter affect the configuration of atmospheric pressure systems that control the sources as well as the temperature and moisture of air masses reaching Kamchatka. (C) 2015 Elsevier B.V. All rights reserved.
KW  - Kamchatka
KW  - North Pacific
KW  - Holocene Climate
KW  - Palaeolimnology
KW  - Diatoms
KW  - Pollen
Y1  - 2015
U6  - https://doi.org/10.1016/j.gloplacha.2015.07.011
SN  - 0921-8181
SN  - 1872-6364
VL  - 134
SP  - 101
EP  - 117
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Nazarova, Larisa B.
A1  - de Hoog, Verena
A1  - Hoff, Ulrike
A1  - Dirksen, Oleg
A1  - Diekmann, Bernhard
T1  - Late Holocene climate and environmental changes in Kamchatka inferred from the subfossil chironomid record
JF  - Quaternary science reviews : the international multidisciplinary research and review journal
N2  - This study presents a reconstruction of the Late Holocene climate in Kamchatka based on chironomid remains from a 332 cm long composite sediment core recovered from Dvuyurtochnoe Lake (Two-Yurts Lake, TYL) in central Kamchatka. The oldest recovered sediments date to about 4500 cal years BP. Chironomid head capsules from TYL reflect a rich and diverse fauna. An unknown morphotype of Tanytarsini, Tanytarsus type klein, was found in the lake sediments. Our analysis reveals four chironomid assemblage zones reflecting four different climatic periods in the Late Holocene. Between 4500 and 4000 cal years BP, the chironomid composition indicates a high lake level, well-oxygenated lake water conditions and close to modern temperatures (similar to 13 degrees C). From 4000 to 1000 cal years BP, two consecutive warm intervals were recorded, with the highest reconstructed temperature reaching 16.8 degrees C between 3700 and 2800 cal years BP. Cooling trend, started around 1100 cal years BP led to low temperatures during the last stage of the Holocene. Comparison with other regional studies has shown that termination of cooling at the beginning of late Holocene is relatively synchronous in central Kamchatka, South Kurile, Bering and Japanese Islands and take place around 3700 cal years BP. From ca 3700 cal years BP to the last millennium, a newly strengthened climate continentality accompanied by general warming trend with minor cool excursions led to apparent spatial heterogeneity of climatic patterns in the region. Some timing differences in climatic changes reconstructed from chironomid record of TYL sediments and late Holocene events reconstructed from other sites and other proxies might be linked to differences in local forcing mechanisms or caused by the different degree of dating precision, the different temporal resolution, and the different sensitive responses of climate proxies to the climate variations. Further high-resolution stratigraphic studies in this region are needed to understand the spatially complex pattern of climate change in Holocene in Kamchatka and the surrounding region.
KW  - Kamchatka
KW  - Holocene
KW  - Chironomids
KW  - Palaeoclimate
KW  - Temperature
Y1  - 2013
U6  - https://doi.org/10.1016/j.quascirev.2013.01.018
SN  - 0277-3791
VL  - 67
IS  - 9
SP  - 81
EP  - 92
PB  - Elsevier
CY  - Oxford
ER  -